1 files changed, 88 insertions, 0 deletions
diff --git a/libs/bitfield-c/src/bitfield/8byte.h b/libs/bitfield-c/src/bitfield/8byte.h
new file mode 100644
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+++ b/libs/bitfield-c/src/bitfield/8byte.h
@@ -0,0 +1,88 @@
+#ifndef __8BYTE_H__
+#define __8BYTE_H__
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Public: Reads a subset of bits into a uint64_t.
+ *
+ * source - the bytes in question.
+ * offset - the starting index of the bit field (beginning from 0).
+ * bit_count - the width of the bit field to extract.
+ * data_is_big_endian - if the data passed in is little endian, set this to false and it
+ *      will be flipped before grabbing the bit field.
+ *
+ * Bit fields are positioned according to big-endian bit layout.
+ *
+ * For example, the bit layout of the value "42" (i.e. 00101010 set at position
+ * 14 with length 6 is:
+ *
+ *     000000000000001010100000000000000000000000000000000000000000000
+ *
+ * and the same value and position but with length 8 is:
+ *
+ *     000000000000000010101000000000000000000000000000000000000000000
+ *
+ * If the architecture where is code is running is little-endian, the input data
+ * will be swapped before grabbing the bit field.
+ *
+ * Examples
+ *
+ *  uint64_t value = get_bitfield(data, 2, 4);
+ *
+ * Returns the value of the requested bit field, right aligned in a uint64_t.
+ */
+uint64_t eightbyte_get_bitfield(uint64_t source, const uint16_t offset,
+        const uint16_t bit_count, const bool data_is_big_endian);
+
+/* Public: Return a single nibble from the payload, with range checking.
+ *
+ * source - the source payload.
+ * nibble_index - the index of the nibble to retreive. The leftmost nibble is
+ *      index 0.
+ * data_is_big_endian - if the data passed in is little endian, set this to false and it
+ *      will be flipped before grabbing the bit field.
+ *
+ * Returns the retreived nibble, right aligned in a uint8_t.
+ */
+uint8_t eightbyte_get_nibble(const uint64_t source, const uint8_t nibble_index,
+        const bool data_is_big_endian);
+
+/* Public: Return a single byte from the payload, with range checking.
+ *
+ * source - the source byte array.
+ * byte_index - the index of the byte to retreive. The leftmost byte is index 0.
+ * data_is_big_endian - if the data passed in is little endian, set this to false and it
+ *      will be flipped before grabbing the bit field.
+ *
+ * Returns the retreived byte.
+ */
+uint8_t eightbyte_get_byte(const uint64_t source, const uint8_t byte_index,
+        const bool data_is_big_endian);
+
+/* Public: Set the bit field in the given data array to the new value.
+ *
+ * destination - a byte array with size at least offset + bit_count.
+ * value - the value to set in the bit field.
+ * offset - the starting index of the bit field (beginning from 0).
+ * bit_count - the number of bits to set in the data.
+ *
+ * Returns true if the bit_count is enough to fully represent the value, and
+ *      false if it will not fit.
+ */
+bool eightbyte_set_bitfield(uint64_t value,
+        const uint16_t offset, const uint16_t bit_count, uint64_t* destination);
+
+/* Private: Determine the index of the last bit used.
+ */
+uint8_t find_end_bit(const uint16_t num_bits);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // __8BYTE_H__